CVE-2026-98262

Summary

In the Linux kernel, the following vulnerability has been resolved:

ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY

A user reported that commit 105c42566a55 ("ata: ahci: force 32-bit DMA for JMicron JMB582/JMB585") made the JMicron JMB585 unusable on his board.

The failure is seen as soon as the ahci driver is probed, and booting with iommu=off does not solve the problem.

Looking at the AHCI specification, PxCLBU and PxFBU are both read only '0' for HBAs that do not support 64-bit addressing.

For HBAs that do support 64-bit addressing, the registers are read write, with a reset value that is Implementation Specific.

When using the AHCI_HFLAG_32BIT_ONLY flag, the HBA does support 64-bit addressing, and a 32-bit DMA mask is set by simply clearing HOST_CAP_64. Thus, in this case, we need to explicitly clear the registers to 0.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < 0191c9ff23ef1678dbfb5ad253a2dee92feb5d71affected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < 8f510f68208a1f673d7c7234a687be4671490e9caffected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < 4719424bb7cb9f20b73986bcb72dd528f0e5c6ebaffected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < a5a8b4737f68bbac8aa0685af0c8921e6003c22baffected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < b28a17d4a9bb0aa38b48681c3927b012ba40eabeaffected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < b691a3e244278362e552439d6d3ee5a5d3703488affected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < 7912ad8fb5233bb8cfe21d50df639c7f4854ff9daffected
LinuxLinuxc7a42156d99bcea7f8173ba7a6034bbaa2ecb77c < 82e47533221d4746947b74d2e79a478c36c6433aaffected
LinuxLinux2.6.22affected
LinuxLinux0 < 2.6.22unaffected
LinuxLinux5.10.271 <= 5.10.*unaffected
LinuxLinux5.15.222 <= 5.15.*unaffected
LinuxLinux6.1.189 <= 6.1.*unaffected
LinuxLinux6.6.158 <= 6.6.*unaffected
LinuxLinux6.12.112 <= 6.12.*unaffected
LinuxLinux6.18.54 <= 6.18.*unaffected
LinuxLinux7.2.8 <= 7.2.*unaffected
LinuxLinux7.3-rc4 <= *unaffected

Weaknesses

References